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I have performed Dot Tune several times and followed all the steps. The 7D only allows one adjustment parameter.
It really depends. How wide is the spread between 70mm and 200mm? If it's not that wide, then you could use an average. The other option is to use the MA setting that corresponds to the focal length you use the most.
On my 7D, my 70-200II was pretty consistent across the range, I think it turned out to be a -3, using FoCal. I haven't even bothered to MA it on my 1DMkIV - doesn't seem like it needs it.
My 100-400 had a pretty wide range when MA'd on the 7D using FoCal. I used an average for the 200-400mm focal lengths. I have also MA'd the 100-400 on the 1DMkIV using Dot-tune, and the range was much tighter.
So why the difference, problem with the 7D or the 100-400? The 7D MA'd fine on the 70-200, so that would suggest the lens has an issue. But the lens MA'd fine on the MKIV.
This crazy stuff is why I would be hesitant to send anything in to Canon to be calibrated together, especially if you have more than one body.
Edited on Aug 25, 2014 at 03:11 PM · View previous versions